The operation is fairly obvious but I've included an animation for clarity, basically as the relief valve pops off, the piston is forced down by the return spring allowing a marble to be released. As the chamber re-pressurises the piston is forced back up, blocking the barrel and holding the next marble in place, and the cycle is continued.

The advantage of this design is that it has the performance of a burst disk valve, with instant "opening time" and no dead space, so the individual marbe energy should be quite impressive. The rate of fire could be tuned by adjusting the rate of flow to the piston chamber or the pop off valve release pressure.

No plans to build this is as yet as my plate is already quite full at the moment but it's potentially on my "to do" list

Look at my valvess prototype, you only need a small protrusion inside the barrel to block it off (assuming your marble is a tight fit in the barrel) - it's the ammo that provides the strength to hold the pressure, all the piston has to do is stop it from rolling forward.

JSR that is quite simply beautiful, no dead space, no burst disc (power like one though). You don't need me to tell you your a f*&^%n gem!

I could imagine much trouble with the seals and spring (finding the right one) but this design has so much potential it's not funny! You would have to make the "holding pin" out of some tough stuff too.To sum up i love this idea, it makes me smile inside

Rock on MR JSR

Edit: Just thought, why not have the holding pin contact the outside of the ammo seal, it would be a smoother action i think.

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America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

I have the same question in regards to the ammo as MrC, I think a tube as such filled with ammo and using a piston to push the ammo down would work.Maybe a line from the "pilot" air line to pressurise the ammo "magazine".

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America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

A simple way to achieve "flow adjustment" would be to plumb a schrader valve into the side of your piston housing, you very well know that if you adjust the screw valve inside said valve you can basically use it as a regulator.

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America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

It would be easier to make this on BB scale but it would be less powerful than my ball valve strafer so not worth the effort. You can also potentially use the piston to actuate a Girandoni style reloading mechanism like the one BrianTheBrain had built, meaning you wouldn't be limited to spherical projectiles. There would be leaks, of course, especially with a homemade system, but I think it would still be viable.

jackssmirkingrevenge wrote:It would be easier to make this on BB scale but it would be less powerful than my ball valve strafer so not worth the effort. You can also potentially use the piston to actuate a Girandoni style reloading mechanism like the one BrianTheBrain had built, meaning you wouldn't be limited to spherical projectiles. There would be leaks, of course, especially with a homemade system, but I think it would still be viable.

I think in this case actual power is non-important. Seriously, look at early rifles compared to their modern day "counterparts".You are in my opinion Jack, a modern day revolutionary.And no i'm not saying this to appease

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America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.

Why thank you, I do my best I dion't think I have better ideas than others, but the difference is that the type of construction I use (epoxy, epoxy, epoxy...) is much more versatile that what most others use and therefore I'm in a better position to flesh out my ideas.

Power would be an issue for me, even if a project is of mechanical interest i will tend to give up on it early unless it promises to do some serious damage.

Right now there's the blowback prototype on my workbench, but I might give this some consideration later. Depending on the performance of the blowback, I might even combine the two ideas and use the reciprocating piston to drive the blowback bolt

I agree wiht jack if there isnt any power to start wiht then why bother...It'll end up on a junk heap..power and power and more power!All man eveyr needs and some food,beer,women etc but mainly power or atleast the false feeling of power.